使用 Gmail API 发送电子邮件的方法有两种:
- 您可以直接使用
messages.send
方法发送该消息。 - 您可以使用
drafts.send
方法从草稿发送该消息。
电子邮件以 base64url 编码的字符串在消息资源的 raw
属性中发送。发送电子邮件的概要流程如下:
- 以某种方便的方式创建电子邮件内容,并将其编码为 base64url 字符串。
- 创建新的消息资源,并将其
raw
属性设置为您刚刚创建的 base64url 字符串。 - 调用
messages.send
或drafts.send
(如果发送草稿)发送消息。
根据您选择的客户端库和编程语言,此工作流的详情可能会有所不同。
创建消息
Gmail API 要求 MIME 电子邮件符合 RFC 2822 并且编码为 base64url 字符串。许多编程语言都拥有可简化 MIME 消息创建和编码过程的库或实用程序。以下代码示例演示了如何使用针对各种语言的 Google API 客户端库创建 MIME 消息。
Java
使用 javax.mail.internet
软件包中的 MimeMessage
类可以大大简化电子邮件的创建过程。以下示例展示了如何创建电子邮件(包括标头):
gmail/snippets/src/main/java/CreateEmail.java
import java.util.Properties; import javax.mail.MessagingException; import javax.mail.Session; import javax.mail.internet.InternetAddress; import javax.mail.internet.MimeMessage; /* Class to demonstrate the use of Gmail Create Email API */ public class CreateEmail { /** * Create a MimeMessage using the parameters provided. * * @param toEmailAddress email address of the receiver * @param fromEmailAddress email address of the sender, the mailbox account * @param subject subject of the email * @param bodyText body text of the email * @return the MimeMessage to be used to send email * @throws MessagingException - if a wrongly formatted address is encountered. */ public static MimeMessage createEmail(String toEmailAddress, String fromEmailAddress, String subject, String bodyText) throws MessagingException { Properties props = new Properties(); Session session = Session.getDefaultInstance(props, null); MimeMessage email = new MimeMessage(session); email.setFrom(new InternetAddress(fromEmailAddress)); email.addRecipient(javax.mail.Message.RecipientType.TO, new InternetAddress(toEmailAddress)); email.setSubject(subject); email.setText(bodyText); return email; } }
下一步是对 MimeMessage
进行编码,实例化 Message
对象,并将 base64url 编码的消息字符串设置为 raw
属性的值。
gmail/snippets/src/main/java/CreateMessage.java
import com.google.api.services.gmail.model.Message; import java.io.ByteArrayOutputStream; import java.io.IOException; import javax.mail.MessagingException; import javax.mail.internet.MimeMessage; import org.apache.commons.codec.binary.Base64; /* Class to demonstrate the use of Gmail Create Message API */ public class CreateMessage { /** * Create a message from an email. * * @param emailContent Email to be set to raw of message * @return a message containing a base64url encoded email * @throws IOException - if service account credentials file not found. * @throws MessagingException - if a wrongly formatted address is encountered. */ public static Message createMessageWithEmail(MimeMessage emailContent) throws MessagingException, IOException { ByteArrayOutputStream buffer = new ByteArrayOutputStream(); emailContent.writeTo(buffer); byte[] bytes = buffer.toByteArray(); String encodedEmail = Base64.encodeBase64URLSafeString(bytes); Message message = new Message(); message.setRaw(encodedEmail); return message; } }
Python
以下代码示例演示了如何创建 MIME 消息、编码为 base64url 字符串并将其分配到 Message
资源的 raw
字段:
gmail/snippet/send mail/create_draft.py
import base64 from email.message import EmailMessage import google.auth from googleapiclient.discovery import build from googleapiclient.errors import HttpError def gmail_create_draft(): """Create and insert a draft email. Print the returned draft's message and id. Returns: Draft object, including draft id and message meta data. Load pre-authorized user credentials from the environment. TODO(developer) - See https://developers.google.com/identity for guides on implementing OAuth2 for the application. """ creds, _ = google.auth.default() try: # create gmail api client service = build("gmail", "v1", credentials=creds) message = EmailMessage() message.set_content("This is automated draft mail") message["To"] = "[email protected]" message["From"] = "[email protected]" message["Subject"] = "Automated draft" # encoded message encoded_message = base64.urlsafe_b64encode(message.as_bytes()).decode() create_message = {"message": {"raw": encoded_message}} # pylint: disable=E1101 draft = ( service.users() .drafts() .create(userId="me", body=create_message) .execute() ) print(f'Draft id: {draft["id"]}\nDraft message: {draft["message"]}') except HttpError as error: print(f"An error occurred: {error}") draft = None return draft if __name__ == "__main__": gmail_create_draft()
创建带有附件的邮件
创建带有附件的邮件与创建任何其他邮件一样,但将文件作为多部分 MIME 消息上传的过程取决于编程语言。以下代码示例演示了创建带有附件的多部分 MIME 消息的可行方法。
Java
以下示例展示了如何创建多部分 MIME 消息,编码和分配步骤与上文相同。
gmail/snippets/src/main/java/CreateDraftWithAttachment.java
import com.google.api.client.googleapis.json.GoogleJsonError; import com.google.api.client.googleapis.json.GoogleJsonResponseException; import com.google.api.client.http.HttpRequestInitializer; import com.google.api.client.http.javanet.NetHttpTransport; import com.google.api.client.json.gson.GsonFactory; import com.google.api.services.gmail.Gmail; import com.google.api.services.gmail.GmailScopes; import com.google.api.services.gmail.model.Draft; import com.google.api.services.gmail.model.Message; import com.google.auth.http.HttpCredentialsAdapter; import com.google.auth.oauth2.GoogleCredentials; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.IOException; import java.util.Properties; import javax.activation.DataHandler; import javax.activation.DataSource; import javax.activation.FileDataSource; import javax.mail.MessagingException; import javax.mail.Multipart; import javax.mail.Session; import javax.mail.internet.InternetAddress; import javax.mail.internet.MimeBodyPart; import javax.mail.internet.MimeMessage; import javax.mail.internet.MimeMultipart; import org.apache.commons.codec.binary.Base64; /* Class to demonstrate the use of Gmail Create Draft with attachment API */ public class CreateDraftWithAttachment { /** * Create a draft email with attachment. * * @param fromEmailAddress - Email address to appear in the from: header. * @param toEmailAddress - Email address of the recipient. * @param file - Path to the file to be attached. * @return the created draft, {@code null} otherwise. * @throws MessagingException - if a wrongly formatted address is encountered. * @throws IOException - if service account credentials file not found. */ public static Draft createDraftMessageWithAttachment(String fromEmailAddress, String toEmailAddress, File file) throws MessagingException, IOException { /* Load pre-authorized user credentials from the environment. TODO(developer) - See https://developers.google.com/identity for guides on implementing OAuth2 for your application.*/ GoogleCredentials credentials = GoogleCredentials.getApplicationDefault() .createScoped(GmailScopes.GMAIL_COMPOSE); HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(credentials); // Create the gmail API client Gmail service = new Gmail.Builder(new NetHttpTransport(), GsonFactory.getDefaultInstance(), requestInitializer) .setApplicationName("Gmail samples") .build(); // Create the email content String messageSubject = "Test message"; String bodyText = "lorem ipsum."; // Encode as MIME message Properties props = new Properties(); Session session = Session.getDefaultInstance(props, null); MimeMessage email = new MimeMessage(session); email.setFrom(new InternetAddress(fromEmailAddress)); email.addRecipient(javax.mail.Message.RecipientType.TO, new InternetAddress(toEmailAddress)); email.setSubject(messageSubject); MimeBodyPart mimeBodyPart = new MimeBodyPart(); mimeBodyPart.setContent(bodyText, "text/plain"); Multipart multipart = new MimeMultipart(); multipart.addBodyPart(mimeBodyPart); mimeBodyPart = new MimeBodyPart(); DataSource source = new FileDataSource(file); mimeBodyPart.setDataHandler(new DataHandler(source)); mimeBodyPart.setFileName(file.getName()); multipart.addBodyPart(mimeBodyPart); email.setContent(multipart); // Encode and wrap the MIME message into a gmail message ByteArrayOutputStream buffer = new ByteArrayOutputStream(); email.writeTo(buffer); byte[] rawMessageBytes = buffer.toByteArray(); String encodedEmail = Base64.encodeBase64URLSafeString(rawMessageBytes); Message message = new Message(); message.setRaw(encodedEmail); try { // Create the draft message Draft draft = new Draft(); draft.setMessage(message); draft = service.users().drafts().create("me", draft).execute(); System.out.println("Draft id: " + draft.getId()); System.out.println(draft.toPrettyString()); return draft; } catch (GoogleJsonResponseException e) { // TODO(developer) - handle error appropriately GoogleJsonError error = e.getDetails(); if (error.getCode() == 403) { System.err.println("Unable to create draft: " + e.getDetails()); } else { throw e; } } return null; } }
Python
与上一个示例类似,此示例还处理了将消息编码为 base64url 并将其分配给 Message
资源的 raw
字段的过程。
gmail/snippet/send mail/create_draft_with_attachment.py
import base64 import mimetypes import os from email.message import EmailMessage from email.mime.audio import MIMEAudio from email.mime.base import MIMEBase from email.mime.image import MIMEImage from email.mime.text import MIMEText import google.auth from googleapiclient.discovery import build from googleapiclient.errors import HttpError def gmail_create_draft_with_attachment(): """Create and insert a draft email with attachment. Print the returned draft's message and id. Returns: Draft object, including draft id and message meta data. Load pre-authorized user credentials from the environment. TODO(developer) - See https://developers.google.com/identity for guides on implementing OAuth2 for the application. """ creds, _ = google.auth.default() try: # create gmail api client service = build("gmail", "v1", credentials=creds) mime_message = EmailMessage() # headers mime_message["To"] = "[email protected]" mime_message["From"] = "[email protected]" mime_message["Subject"] = "sample with attachment" # text mime_message.set_content( "Hi, this is automated mail with attachment.Please do not reply." ) # attachment attachment_filename = "photo.jpg" # guessing the MIME type type_subtype, _ = mimetypes.guess_type(attachment_filename) maintype, subtype = type_subtype.split("/") with open(attachment_filename, "rb") as fp: attachment_data = fp.read() mime_message.add_attachment(attachment_data, maintype, subtype) encoded_message = base64.urlsafe_b64encode(mime_message.as_bytes()).decode() create_draft_request_body = {"message": {"raw": encoded_message}} # pylint: disable=E1101 draft = ( service.users() .drafts() .create(userId="me", body=create_draft_request_body) .execute() ) print(f'Draft id: {draft["id"]}\nDraft message: {draft["message"]}') except HttpError as error: print(f"An error occurred: {error}") draft = None return draft def build_file_part(file): """Creates a MIME part for a file. Args: file: The path to the file to be attached. Returns: A MIME part that can be attached to a message. """ content_type, encoding = mimetypes.guess_type(file) if content_type is None or encoding is not None: content_type = "application/octet-stream" main_type, sub_type = content_type.split("/", 1) if main_type == "text": with open(file, "rb"): msg = MIMEText("r", _subtype=sub_type) elif main_type == "image": with open(file, "rb"): msg = MIMEImage("r", _subtype=sub_type) elif main_type == "audio": with open(file, "rb"): msg = MIMEAudio("r", _subtype=sub_type) else: with open(file, "rb"): msg = MIMEBase(main_type, sub_type) msg.set_payload(file.read()) filename = os.path.basename(file) msg.add_header("Content-Disposition", "attachment", filename=filename) return msg if __name__ == "__main__": gmail_create_draft_with_attachment()
发送消息
创建消息后,您可以在调用 messages.send
的请求正文中提供此消息,如以下示例所示。
Java
gmail/snippets/src/main/java/SendMessage.java
import com.google.api.client.googleapis.json.GoogleJsonError; import com.google.api.client.googleapis.json.GoogleJsonResponseException; import com.google.api.client.http.HttpRequestInitializer; import com.google.api.client.http.javanet.NetHttpTransport; import com.google.api.client.json.gson.GsonFactory; import com.google.api.services.gmail.Gmail; import com.google.api.services.gmail.GmailScopes; import com.google.api.services.gmail.model.Message; import com.google.auth.http.HttpCredentialsAdapter; import com.google.auth.oauth2.GoogleCredentials; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.util.Properties; import javax.mail.MessagingException; import javax.mail.Session; import javax.mail.internet.InternetAddress; import javax.mail.internet.MimeMessage; import org.apache.commons.codec.binary.Base64; /* Class to demonstrate the use of Gmail Send Message API */ public class SendMessage { /** * Send an email from the user's mailbox to its recipient. * * @param fromEmailAddress - Email address to appear in the from: header * @param toEmailAddress - Email address of the recipient * @return the sent message, {@code null} otherwise. * @throws MessagingException - if a wrongly formatted address is encountered. * @throws IOException - if service account credentials file not found. */ public static Message sendEmail(String fromEmailAddress, String toEmailAddress) throws MessagingException, IOException { /* Load pre-authorized user credentials from the environment. TODO(developer) - See https://developers.google.com/identity for guides on implementing OAuth2 for your application.*/ GoogleCredentials credentials = GoogleCredentials.getApplicationDefault() .createScoped(GmailScopes.GMAIL_SEND); HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(credentials); // Create the gmail API client Gmail service = new Gmail.Builder(new NetHttpTransport(), GsonFactory.getDefaultInstance(), requestInitializer) .setApplicationName("Gmail samples") .build(); // Create the email content String messageSubject = "Test message"; String bodyText = "lorem ipsum."; // Encode as MIME message Properties props = new Properties(); Session session = Session.getDefaultInstance(props, null); MimeMessage email = new MimeMessage(session); email.setFrom(new InternetAddress(fromEmailAddress)); email.addRecipient(javax.mail.Message.RecipientType.TO, new InternetAddress(toEmailAddress)); email.setSubject(messageSubject); email.setText(bodyText); // Encode and wrap the MIME message into a gmail message ByteArrayOutputStream buffer = new ByteArrayOutputStream(); email.writeTo(buffer); byte[] rawMessageBytes = buffer.toByteArray(); String encodedEmail = Base64.encodeBase64URLSafeString(rawMessageBytes); Message message = new Message(); message.setRaw(encodedEmail); try { // Create send message message = service.users().messages().send("me", message).execute(); System.out.println("Message id: " + message.getId()); System.out.println(message.toPrettyString()); return message; } catch (GoogleJsonResponseException e) { // TODO(developer) - handle error appropriately GoogleJsonError error = e.getDetails(); if (error.getCode() == 403) { System.err.println("Unable to send message: " + e.getDetails()); } else { throw e; } } return null; } }
Python
gmail/snippet/发送邮件/send_message.py
import base64 from email.message import EmailMessage import google.auth from googleapiclient.discovery import build from googleapiclient.errors import HttpError def gmail_send_message(): """Create and send an email message Print the returned message id Returns: Message object, including message id Load pre-authorized user credentials from the environment. TODO(developer) - See https://developers.google.com/identity for guides on implementing OAuth2 for the application. """ creds, _ = google.auth.default() try: service = build("gmail", "v1", credentials=creds) message = EmailMessage() message.set_content("This is automated draft mail") message["To"] = "[email protected]" message["From"] = "[email protected]" message["Subject"] = "Automated draft" # encoded message encoded_message = base64.urlsafe_b64encode(message.as_bytes()).decode() create_message = {"raw": encoded_message} # pylint: disable=E1101 send_message = ( service.users() .messages() .send(userId="me", body=create_message) .execute() ) print(f'Message Id: {send_message["id"]}') except HttpError as error: print(f"An error occurred: {error}") send_message = None return send_message if __name__ == "__main__": gmail_send_message()
如果您要尝试发送回复邮件,且希望系统发送该邮件,请确保:
Subject
标头匹配References
和In-Reply-To
标头遵循 RFC 2822 标准。
如需了解如何从草稿发送邮件,请参阅创建草稿。